Mixed alkoxysilyl functional polymers

ABSTRACT

This invention relates to silylated polymers having mixed alkoxy groups on the silyl portion thereof, methods of their preparation, and compositions and reaction products formed therefrom. These alkoxysilylated polymers can be crosslinked when expoesed to atmospheric moisture to become useful elastomers, sealants or adhesives. The presence of different alkoxy groups on the silicon atoms can control or otherwise moderate the cure speeds of these silylated polymers.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to silylated polymers having mixed alkoxygroups on the silyl portion thereof, methods of their preparation, andcompositions and reaction products formed therefrom. Thesealkoxysilylated polymers can be crosslinked when exposed to atmosphericmoisture to become useful elastomers, sealants or adhesives. Thepresence of different alkoxy groups on the silicon atoms can control thecure speeds of these silylated polymers.

[0003] 2. Background of Related Technology

[0004] Alkoxysilylated polymers, in the presence of a catalyst, can becrosslinked by atmospheric moisture under ambient conditions.Compositions based on these type of polymers are often referred to asRTV sealants (or adhesives). The most well known example is RTV siliconesealants.

[0005] Crosslinking of alkoxysilylated polymers involves hydrolysis andcondensation reactions of the alkoxylsilyl group. The cure speed ofcompositions prepared therefrom has conventionally been acceleratedthrough the use of various types and amounts of moisture cure catalysts.However, among the disadvantages of using increased amounts of suchcatalysts to obtain greater cure speeds are potential instability, lossof shelf life and enhanced manufacturing and material costs of suchcompositions.

[0006] The smaller alkoxy groups, e.g. methoxy, are ordinarily morereactive and thus better able to be displaced by another chemicalentity. Therefore, methoxy groups are more desirable for obtainingmoisture curable polymers having faster and/or more controlled curespeeds. Currently, however, the starting materials for making many loweralkoxy group-containing polymers with a variety of backbones, such aspolyethers like polypropylene oxide (“PPO”), are not readilycommercially available. For example, a desirable route for makingsilyl-terminated PPO polymers containing alkoxy groups might includereacting an isocyanatoalkyltrialkoxysilane with an hydroxy terminatedPPO. However, presently trimethoxysilyl-terminated isocyanatoalkylcompounds are not widely commercially available.

[0007] Thus, there is a need for a method of conveniently producing amoisture curable composition which includes a curable polymer having amixture of different alkoxy groups present, at least one of which beinga methoxy group, whereby controlled moisture cure speed is obtained.

SUMMARY OF THE INVENTION

[0008] In accordance with the present invention, moisture cure speed canbe controlled to proceed in a more or less rapid manner, depending onthe identity and number of the alkoxy groups on the curable alkoxysilylpolymer. For example, methoxy and ethoxy groups are contemplated asbeing present concurrently on the silyl groups of the polymers of thepresent invention, though the methoxy groups provide more rapid cure.

[0009] One aspect of the invention relates to the presence of differentalkoxy groups on the silicon atom of a silyl endcapped moisture curablepolymer, whereby controlled cure speed of the moisture curable polymeris obtained. The presence of larger alkoxy groups, such as ethoxy orgreater, slow down the cure while smaller alkoxy groups, such asmethoxy, accelerate it. The overall cure speed is related to the type orcombination of alkoxy group(s) or groups on the silicon. As noted above,the cure speed is faster if the alkoxy group is a better leaving group.Typically, a smaller alkoxy group is a better leaving group. Forexample, a methoxysilylated polymer cures faster than an ethoxysilylatedpolymer or a butoxysilylated polymer.

[0010] Another aspect of the invention relates to a moisture curablecomposition which includes an alkoxylsilyl terminated polymer containingmore than one type of alkoxy group. Desirably, the alkoxy groups are atthe terminal ends of the polymer, though pendant groups are alsocontemplated. The backbone of the polymer can be varied and may bechosen from a wide range of materials. PPO is among the desirablebackbones.

[0011] A further aspect of the present invention relates to a reactionproduct formed from the aforementioned polymer having mixed alkoxysilylfunctional groups and a catalyst.

[0012] In still another aspect of the invention, there is provided amethod for preparing mixed alkoxysilyl polymers via an alkoxy exchangereaction. This process includes mixing a polymer having at least onealkoxysilyl group present, an alkoxysilane and a catalyst. Desirably,the alkoxysilane contains a methoxy group which exchanges with a highercarbon number alkoxy on the alkoxysilyl polymer. The resultant alkoxyexchange reaction desirably provides a mixture of different alkoxygroups, e.g. methoxy, ethoxy and the like on the reactive polymer. Thealkoxy exchange can occur slowly at room temperature, but desirablyoccurs at higher temperatures in the presence of a catalyst.

[0013] In yet another aspect of the invention, there is included areactive polymer having the structure:

[0014] wherein R is a hydrocarbon diradical which may include heteroatomand/or silicone-containing groups or linkages; A and A′ may be eachC₁₋₃₀ linear or branched, substituted or unsubstituted aliphatic groupsor aromatic-containing groups, with or without interuption by a carboxy,carbamate, carbonate, ureido, urethane or sulfonate linkage; n may be 0or 1; R¹ and R² may be each substituted or unsubstituted C₁₋₁₂ alkyl oraryl groups; R³ is a C₁₋₁₂ alkyl, alkenyl, alkoxy, aminoalkyl or arylgroup, or a (meth)acryloxyalkyl group.

[0015] This polymer can be combined with a catalyst and other componentsto form a curable composition.

[0016] A further aspect of the invention includes a curable compositionwhich includes:

[0017] (a) a polymer having the structure

[0018] wherein R is a hydrocarbon diradical which may include heteroatomand/or silicone-containing groups or linkages; A and A′ may be eachC₁₋₃₀ linear or branched, substituted or unsubstituted aliphatic groupsor aromatic-containing groups, with or without interuption by a carboxy,carbamate, carbonate, ureido, urethane or sulfonate linkage; n may be 0or 1; R¹ and R² may be each substituted or unsubstituted C₁₋₁₂ alkyl oraryl groups; R³ is a C₁₋₁₂ alkyl, alkenyl, alkoxy, aminoalkyl or arylgroup, or a (meth)acryloxyalkyl group.

[0019] (b) a catalyst.

[0020] A further aspect of the invention includes the reaction productof:

[0021] (a) a polymer having at least one pendent or terminal alkoxysilylgroup thereon and being a member selected from the group consisting ofpolyethers, polyolefins, polyesters, polyurethanes, polysiloxanes,poly(meth)acrylates, polyepoxides and combinations thereof;

[0022] (b) an alkoxysilane; and

[0023] (c) a catalyst.

[0024] Still a further aspect of the invention includes a method ofmaking an alkoxysilyl endcapped polymer, which includes the steps ofreacting a first reactant having the structure:

HO—R—OH

[0025] wherein R is a hydrocarbon diradical which may include heteroatomand/or silicone-containing groups or linkages, with a second reactanthaving one end terminating with an isocyanate group and another endterminating with a silyl group having at least two alkoxy groupsattached to a silicon atom thereof, and providing a third reactant, suchas an alkoxy silane. An example of the first reactant is hydroxylterminated PPO; an example of the second reactant isisocyanatopropyltriethoxy silane; and examples of the third reactantinclude methyltrimethoxy silane, methyltriethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, and the like.

[0026] Another aspect of the invention includes reacting an organicalcohol terminated compound such as PPO terminated with OH groups, withan isocyanatoalkyltrialkoxysilane, such asisocyanatopropyltriethoxysilane, in the presence of a catalyst such as atin catalyst, or desirably a titanium alkylate such as titaniumtetraisopropoxide, or a metal alkoxide such as sodium methoxide. Theresultant composition provides a polymer which can then undergo alkoxyexchange when placed in the presence of a different alkoxy group such asa methoxysilane. This results in a mixed alkoxysilyl polymer compositionhaving controlled, moderated or accelerated moisture cure speed.

[0027] The preparation of the mixed alkoxysilyl polymer can also beperformed concurrently with the compounding of a moisture curablecomposition. For example, the polymer having at least one alkoxysilylgroup, the alkoxysilane and the catalyst can be admixed with othercomponents used to make the final moisture curable product. In thismethod, the alkoxy exchange occurs in situ in the final product withoutsubjecting the controlled moisture curing reactive polymer per se to apre-reaction or formation step prior to compounding.

[0028] Another aspect of the invention includes mixing a polymer havingat least one alkoxysilyl group with an alcohol in the presence of acatalyst. The mixture is then aged at ambient temperature or elevatedtemperature to permit alkoxy exchange, thereby forming a mixedalkoxysilyl-containing reactive polymer.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The invention relates to mixed alkoxysilyl polymers, curablepolymers and compositions made therefrom.

[0030] The present invention recognizes that the cure speeds of polymerscan be manipulated by putting different alkoxy groups on the silyl endgroups of polymers encapped therewith. Cure speeds decrease in the orderof MeO>EtO and higher. In one aspect of the invention, there is a methodof providing mixed alkoxsilyl endcapping of polymers by reacting anhydroxy terminated polypropylene oxide polymer with a3-isocyanatopropyltriethoxysilane and mixing the resultant reactionproduct with an alkoxysilane having a different alkoxy group, e.g. amethoxy group, than the reaction product, and allowing alkoxy exchangeto occur, desirably in the presence of a catalyst, to form the mixedalkoxysilyl polymer. Cure speed of the resultant polymer is intermediatebetween those endcapped with pure 3-isocyanatopropyltrimethoxysilane andthose encapped with pure 3-isocyanatopropyltriethoxysilane.

[0031] Curable polymers made and used in accordance with the presentinvention include, but are not limited to, those having the structure:

[0032] wherein R is a hydrocarbon diradical which may include heteroatomand/or silicone-containing groups or linkages; A and A′ may be eachC₁₋₃₀ linear or branched, substituted or unsubstituted aliphatic groupsor aromatic-containing groups, with or without interuption by A may alsobe a carboxy, carbamate, carbonate, ureido, urethane or sulfonatelinkage; n may be 0 or 1; R¹ and R² may be each substituted orunsubstituted C₁₋₁₂ alkyl or aryl groups; R³ is a C₁₋₁₂ alkyl, alkenyl,alkoxy, aminoalkyl or aryl group, or a (meth)acryloxyalkyl group.

[0033] Additional examples of R backbones include alkyd resins, oilmodified alkyd resins, unsaturated polyesters, natural oils, (e.g.,linseed, tung, soybean), epoxides, nylons, thermoplastic polyesters(e.g., polyethyleneterephthalate, polybutyleneterephthalate),polycarbonates, polyethylenes, polybutylenes, polystyrenes,polypropylenes, ethylene propylene co- and terpolymers, acrylics(homopolymer and copolymers of acrylic acid, acrylates, mathacrylates,acrylamides, their salts, hydrohalides, and the like), phenolic resins,polyoxymethylene (homopolymers and copolymers), polyurethanes,polysulfones, polysulfide rubbers, nitrocelluloses, vinyl butyrates,vinyls (e.g., vinyl chloride and/or vinyl acetate containing polymers),ethyl cellulose, the cellulose acetates and butyrates, viscose rayon,shellac, waxes, ethylene copolymers (e.g., ethylenevinyl acetatecopolymers, ethyleneacrylic acid copolymers, ethyleneacrylatecopolymers), organic rubbers, silicone greases, resins and rubbers andthe like. Still additional examples of R include polyethers, such aspolyethylene oxide (“PEO”), PPO and polyTHF.

[0034] R may also include natural rubber; those formed from thehomopolymerization of butadiene and its homologues and derivatives suchas: cis-1,4-polyisoprene; 3,4-polyisoprene; cis-1,4-polybutadiene;trans-1,4-polybutadiene; 1,2-polybutadiene; and those formed from thecopolymerization of butadiene and its homologues and derivatives withone or more copolymerizable monomers containing ethylenic unsaturationsuch as styrene and its derivatives, vinyl-pyridine and its derivatives,acrylonitrile, isobutylene and alkyl-substituted acrylates such asmethylmethacrylate. Examples include styrene-butadiene copolymer rubbercomposed of various percentages of styrene and butadiene and employingthe various isomers of butadiene as desired (hereinafter “SBR”);terpolymers of styrene, isoprene and butadiene polymers, and theirvarious isomers; acrylonitrile-based copolymer and terpolymer rubbercompositions; and isobutylene-based rubber compositions; or a mixturethereof, as described in, for example, U.S. Pat. Nos. 4,530,959;4,616,065; 4,748,199; 4,866,131; 4,894,420; 4,925,894; 5,082,901; and5,162,409.

[0035] Other suitable organic polymers useful as R backbones arecopolymers of ethylene with other high alpha olefins such as propylene,butene-1 and pentene-1 and a diene monomer. The organic polymers may beblock, random, or sequential and may be prepared by emulsion (e.g.e-SBR) or solution polymerization processes (e.g., s-SBR). Additionalpolymers which may be used include those which are partially or fullyfunctionalized including coupled or star-branched polymers. Additionalspecific examples of functionalized organic rubbers includepolychloroprene, chlorobutyl and bromobutyl rubber as well as brominatedisobutylene-co-paramethylstyrene rubber. The preferred organic rubbersare polybutadiene, s-SBR and mixtures thereof.

[0036] Silicone rubbers which are useful as R include organicpolysiloxane compositions in which the organic polysiloxane is linear orbranched, and optionally may contain, in addition to the hydrocarbongroups, certain reactive groups such as for example, hydroxyl,hydrolyzable groups, alkenyl groups such as vinyl, hydrogen, fluoro, andphenyl. Further examples are given in U.S. Pat. No. 5,009,874, thedisclosure of which is hereby expressly incorporated herein byreference.

[0037] Other useful R backbone polymers include acrylonitrile-butadienerubber (“NBR”), fluorine-containing rubber, epychlorohydrin rubber,butyl rubber, halogenated butyl rubber, brominatedisobutylene/p-methylstyrene copolymer rubber, chloroprene rubber,ethylene/acrylate copolymer rubber and epoxidized natural rubber,ethylene/propylene/diene rubber (“EPDM”) and the like.

[0038] The curable polymers of the present invention desirably have aviscosity in the range of about 10 cps to about 1,000,000 cps and moredesirably about 1,000 cps to about 100,000 cps.

[0039] The invention further includes alkoxysilyl polymers and polymercompositions, and methods of preparing same through an alkoxy exchangereaction. One method of the present invention includes mixing acomposition which includes:

[0040] (a) a polymer within structure I,

[0041] (b) an alkoxysilane in a sufficient amount to permit alkoxyexchange with the alkoxylsilyl groups of structure I, and

[0042] (c) a catalyst.

[0043] This invention includes the composition based on the mixedalkoxysilyl polymer formed from mixing components (a), (b) and (c).

[0044] Component (a) may be chosen from a wide variety of reactivepolymers, as set forth herein.

[0045] In structure I, linkage A between the alkoxysilyl group and thepolymer backbone R is desirably resistant to common chemicals such aswater, solvents, and mild acids and bases. Linkage A is intended to be astable linkage. Linkage A may optionally be present in cases where R isterminated with appropriate atoms, such as O, to ensure a stable bondwith the terminal alkoxysilyl groups. Particularly desirable examples ofA include C₁₋₄ alkylene linkages, such as ethylene or propylene. Otherparticularly desirable examples of A include those having carboxy,carbonate, carbamate, ureido, urethane or sulfonate linkage containedwithin. When including these groups, A is desirably attached to theterminal silyl group by a branched liner, substituted or unsubstituted,aliphatic, cycloaliphatic or aromatic group in order to improvestability of the spacer. Examples of such A groups include:

[0046] The inventive alkoxy silyl polymers may further include moistureand/or UV/moisture curable polymers, such as silicon polymers (see U.S.Pat. Nos. 4,528,081, 4,675,346, and 4,699,802, the disclosure of each ofwhich being expressly incorporated herein by reference).

[0047] wherein R⁸ is a branched or linear, substituted or unsubstitutedaliphatic, cycloaliphatic or aromatic group and _(P) is an integer from1-4. R⁸ is desirably methylene, ethylene or propylene.

[0048] Component (b) is an alkoxysilane with the structure of R⁴_(n)Si(OR¹)_(4−n), where n=0, 1 or 2. The preferred alkoxysilane has n=0or 1. R⁴ is a monovalent radical. It includes aryl, alkyl, vinyl, allyl,organofunctional aryl and organofunctional alkyl. Some examples of R⁴are 3-aminopropyl, methacryloxypropyl and chloropropyl. R¹ is amonovalent radical different from R², except it may be the same as R²where A is a carboxy, carbamide, ureido or urethane group. It includesaryl and alkyl. Lower alkyl C₁₋₃, such as ethoxy, is desirable.

[0049] Component (c) may be selected from a variety of known catalysts.For instance, the catalyst may be chosen from transition metalcomplexes, tin catalysts (such as dialkyl tin dicarboxylates), titaniumcatalysts (such as metal alkoxide catalysts), bases, acids (such ascarboxylic acids), quaternary salts, amines, phosphines, titanates (suchas alkyl titanates), and tetraalkylphosphonium salts. Catalysts may bepresent in amounts of about 0.01 to about 1.0% and desirably about 0.5to about 0.5% by weight of the total composition. It further includesother conventional catalysts known to be active in reactions ofalkoxysilanes. Photoinitiators, such as visible and UV photoinitiators,may also be used.

[0050] According to the method of the present invention, the combinationor mixture of the three components, (a), (b) and (c), is aged at ambienttemperature or at elevated temperatures. The resulting compositiondesirably includes polymer and silane containing both R²O and R¹Ogroups. This mixture cures by atmospheric moisture at a different speedfrom that of the original unaged mixture or the starting materials. Thedifference in cure speed depends on the nature of the R²O and R¹Ogroups.

[0051] In preparing the reactive polymers of structure I, it isdesirable to do so using a catalyst other than a tin-based catalyst.Although tin-based catalysts are useful for moisture curing the formedreactive polymers, when used in the preparation of such reactivepolymers residual catalyst from their manufacture may result in poorshelf life and instability in the final curable composition. It has beendiscovered that a further advantage of the present invention may becaptured when catalysts, such as titanium catalysts including titaniumtetraisopropoxide, or metal alkoxide catalysts such as sodium methoxideare employed. The aforementioned catalysts are easily quenchedsubsequent to the formation of the reactive polymer, thereby preventingactive residue catalyst from causing premature curing. Additionally,titanium tetraisopropoxide is a particularly useful catalyst forenhancing the rate of the transesterification reaction, though a lessefficient condensation catalyst. This allows for the enhanced rate offormation of the mixed alkoxy end groups without sacrificing stability.These catalyst are available commercially from E.I. DuPont de Nemours.Though the catalysts may be used in the range of about 0.01 to about0.5%, desirably about 0.1 to about 0.3%, the catalysts (which are nontin based ones) have the added advantage of achieving similar curespeeds using smaller amounts of catalyst, e.g., about 0.1 to about 0.2%as compared with 0.5% (tin-based).

[0052] Another method of preparing mixed alkoxysilyl polymers through analkoxy exchange reaction includes mixing:

[0053] (a) a polymer having at least one alkoxysilyl group,

[0054] (b) an alcohol, and

[0055] (c) a catalyst.

[0056] Component (b) is an alcohol with the structure of R⁷OH. R⁷ is amonovalent radical different from R². It includes aryl and alkyl. Alkylis preferred.

[0057] According to this method of the present invention, the mixture ofthe three components, (a), (b) and (c), is aged at ambient temperatureor at elevated temperatures. The resulting composition includescatalyst, polymer containing both R²O and R¹O groups, and R²OH and R¹OH.The alcohols are removed with by evaporation at various temperatures andunder various pressures. This resulting composition cures by atmosphericmoisture at a different t speed from that of the original mixture. Thedifference in cure speed depends on the nature of the R²O and R¹Ogroups.

[0058] The invention also provides a method of controlling the curespeed of an alkoxy silyl functional polymer, the steps of which includeproviding an alkoxy silyl functional polymer having two or moredifferent alkoxy groups; providing a cure catalyst therefor; andexposing the alkoxy silyl functional polymer and the catalyst toconditions sufficient to cure the alkoxy silyl functional polymer. Theidentity and/or amount of the two or more different alkoxy groupscontrols the cure speed of the alkoxy silyl functinal polymer having twoor more different alkoxy groups thereon.

[0059] The compositions in the present invention can include variousother components useful in the manufacturing of moisture curableproducts. For example, various moisture catalysts, fillers, stabilizers,inhibitors, reactive diluents, viscosity modifiers and the like may beincorporated at useful ranges for their intended purposes.

[0060] It is known that triethoxysilane endcapped polypropylene oxidepolymers moisture cure at much slower speeds than trimethoxysilaneendcapped counterparts. The present invention seeks to provide a mixtureof alkoxysilyl terminated polymers to control and desirably toaccelerate the moisture curing capability of the resultant reactivepolymers.

EXAMPLES Example 1

[0061] ViSi(OE)₃ was mixed with equal weight of ViSi(OMe)₃ or MeOH inthe presence of 1% UL-45 (a tin catalyst from Witco). The silanecompositions were monitored using ²⁹Si NMR spectroscopy. As seen fromdata set forth in Table 1, alkoxy exchange occurred. TABLE 1 AlkoxyExchange Reactions Sample Reaction Reaction Mol Percent in ProductMixture No. Composition* time (min.) (° C.) T ViSi(OMe)₃ ViSi(OMe)₂OEtViSi(OMe)(OEt)₂ ViSi(OEt)₃ 1 50% ViSi(OEt)₃ + 50% 30 RT 54.96 0.95 1.0443.05 ViSi(OMe)₃ 2 50% ViSi(OEt)₃ + 50% 60 RT 52.21 3.03 1.94 42.82ViSi(OMe)₃ 3 50% ViSi(OEt)₃ + 50% 480 RT 46.79 8.86 6.16 38.19ViSi(OMe)₃ 4 50% ViSi(OEt)₃ + 50% 1020 RT 40.99 16.17 9.79 33.05ViSi(OMe)₃ 5 50% ViSi(OEt)₃ + 50% 3120 RT 25.6 32.28 18.91 19.21ViSi(OMe)₃ 6 50% ViSi(OEt)₃ + 50% 14400 RT 16.73 39.65 32.69 10.92ViSi(OMe)₃ 7 50% ViSi(OEt)₃ + 50% 60 80 27.61 32.16 18.81 21.43ViSi(OMe)₃ 8 50% ViSi(OEt)₃ + 50% 1440 RT 21.42 24.06 22.31 32.21 MeOH 950% ViSi(OEt)₃ + 50% 240 50 26.74 42.88 22.74 7.64 MeOH

Example 2

[0062] Polymer A (a triethoxysilylated polypropylene oxide) was preparedby heating a mixture of 400 grams ACCLAIM 4200 (a polypropylene oxidepolymer with OH endgroups from Lyondell) with 52 grams SILQUEST A1310(isocyanatopropyltriethoxy silane from Witco) in the presence of 1.5grams UL-28 (a Sn catalyst from Witco) at 30-60 C for 3 hours. SampleNos. 10-12 were prepared in this way with the amounts noted in Table 2a,with Sample No. 10 acting as a control. Mixture of Polymer A with UL-45(a tin catalyst from Witco) and methoxysilanes were used in several NMRexperiments. The results set forth in Table 2b indicate that extensivealkoxy exchange reactions occurred at the 50° C. temperature and overthe period of time in days noted. TABLE 2a Alkoxy Exchange ReactionsSample No./Wt. % Component 10 11 12 Polymer A 99.80 98.71 98.71 UL-45(Sn catalyst) 0.20 0.20 0.20 ViSi(MeO)₃ 1.10 Aminopropyltromethoxy 1.10Silane Total 100.00 100.00 100.00

[0063] TABLE 2b Alkoxy Exchange Reactions Sample No./relative molarconcentration 10 10 11 11 11 11 12 12 Age at 50° C., days 8 35 9 17 2244 18 43 (EtO)₃Si - capped PPO 1 1 1 1 1 1 1 1 (EtO)₂(MeO)Si - 0.2020.312 0.415 0.407 0.296 0.35 capped PPO (EtO)(MeO)₂Si - 0.054 0.0480.069 0.063 0.03 0.039 capped PPO ViSi(MeO)₃* 0 0 0 0 ViSi(MeO)₂(EtO)0.088 0.023 0.053 0.053 ViSi(MeO)(EtO)₂ 0.091 0.064 0.103 0.125H₂NPrSi(MeO)₃* 0 0 H₂NPrSi(MeO)₂(EtO) 0.031 0.092 H₂NPrSi(MeO)(EtO)₂0.172 0.393

Example 3

[0064] Polymer B (a triethoxysilylated polypropylene oxide) was preparedby heating a mixture of 450 grams ACCLAIM 12200 (a polypropylene oxidepolymer with OH endgroups from Lyondell) with 20.2 grams SILQUEST A1310(isocyanatopropyltriethoxy silane from Witco) in the presence of 0.1grams UL-28 (a tin catalyst from Witco) at 30-60° C. for 3 hours.

[0065] Both Polymer A and Polymer B were used to prepare moisturecurable compositions (Sample No. 13—Sample No. 22 in Table 3a). Curespeeds of these compositions accelerated with time. The cureacceleration was observed to be faster at 50° C. than at roomtemperature. Table 3b shows these and other observations of performance.TABLE 3a Cure Times of Aged Compositions (Effects of Alkoxy ExchangeReactions) Sample No./Wt. % Components 13 14 15 16 17 18 19 20 21 22Polymer B - 99.26 98.77 98.28 98.77 98.28 (EtO)₃Si PPO capped PolymerA - 99.70 94.79 94.97 94.79 93.50 (EtO)₃Si PPO capped Sn catalyst 0.300.47 0.28 0.47 0.50 0.50 0.49 0.49 0.49 0.49 ViSi(MeO)₃ 0.00 4.74 0.000.00 1.00 0.49 0.98 ViSi(EtO)₃ 0.49 0.98 NH₂PrSi(MeO)₃ 0.25 0.25% 0.250.25 0.25 MeOH 0.00 0.00 4.75 4.74 5.00

[0066] TABLE 3b Cure Times of Aged Compositions (Effects of AlkoxyExchange Reactions) Sample No. Physical Properties 13 14 15 16 17 18 1920 21 22 Aged Temperature, ° C. RT RT RT RT RT RT RT RT RT RT Aged Time,days 0 0 0 0 0 0 0 0 0 0 Skin Over Time, min. 480 1440 450 300 50 30 100200 95 125 Tack Free Time, min. 1200 420 120 195 295 420 320 390 AgedTemperature, ° C. RT RT RT RT RT RT RT RT RT RT Aged Time, days 1 1 1 11 1 1 1 1 1 Skin Over Time, min. 360 1440 360 120 50 25 88 180 80 100Tack Free Time, min. 1440 90 180 300 450 330 400 Aged Temperature, ° C.50 50 50 50 50 Aged Time, days 1 1 1 1 1 Skin Over Time, min. 25 45 6568 100 Tack Free time, min. 180 190 200 250 400 Aged Temperature, ° C.RT RT RT RT RT RT RT RT RT RT Aged Time, days 69 69 69 69 69 3 3 3 3 3Skin Over Time, min. 300 300 110 27 22 22 60 120 62 120 Tack Free Time,min. 255 60 75 130 140 300 150 280 Aged Temperature, ° C. 50 50 50 50 50Aged Time, days 3 3 3 3 3 Skin Over Time, min. 20 20 20 60 90 Tack FreeTime, min. 120 120 120 160 240

Example 4

[0067] Polymer C (a trimethoxysilylated polypropylene oxide) wasprepared by heating a mixture of 914.4 grams ACCLAIM 12200 (apolypropylene oxide polymer with OH endgroups, available commerciallyfrom Lyondell) with 50.4 grams SILQUEST A1310(isocyanatopropyltrimethoxy silane, available commercially from Witco)in the presence of 0.1 grams METATIN 740 (a tin catalyst from Acima) at70-80° C. for 1 hour.

[0068] Polymer C was used to prepare moisture curable compositions(Sample No. 23—Sample No. 32 in Table 4a). Table 4b shows performancedata for these samples. TABLE 4a Cure Times of Aged Compositions (Effectof Different Catalysts on Alkoxy Exchange Reactions) Sample No./Wt. %Components 23 24 25 26 27 28 29 30 31 32 Polymer C - (EtO)₃Si PPO 96.596.5 96.5 96.5 96.5 96.5 96.5 96.5 96.5 96.5 capped Ti(OiPr)₄ catalyst0.3 0.3 0.3 0.3 Sn catalyst 0.2 0.2 0.2 0.2 0.5 0.5 0.5 0.5 0.5 0.5ViSi(OMe)₃ 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 NH₂NH₂CH₂NHPrSi(OMe)₃1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

[0069] TABLE 4b Cure Times of Aged Compositions (Effect of DifferentCatalysts on Alkoxy Exchange Reactions) Sample No./Wt. % PhysicalProperties 23 24 25 26 27 28 29 30 31 32 Aged Temperature, ° C. RT RT 5050 RT 50 50 50 50 50 Aged Time, min. 30 1440 120 240 1440 120 240 360480 1440 Skin Over Time, min. 90  30 30 30  345 315 285 255 195 45

Example 5

[0070] Polymer D (a trimethoxysilylated polypropylene oxide) wasprepared by heating a mixture of 920 grams ACCLAIM 12200 (apolypropylene oxide polymer with OH endgroups from Lyondell) with 44.9grams SILQUEST Y5187 (isocyanatopropyltrimethoxysilane from Witco) inthe presence of 0.1 grams METATIN 740 (a tin catalyst from Acima) at70-80° C. for 1 hour.

[0071] Both Polymer C and Polymer D were used to prepare moisturecurable compositions (Sample No. 33—Sample No. 37 in Table 5a). Curespeeds were detected after aging at 70° C. Before curing 0.2% Sncatalyst and 1% NH₂CH₂CH₂NHPrSi(OMe)₃ were added at room temperature.Table 5b shows performance data for these samples. TABLE 5a Cur Times ofAged Compositions (Effects of Alkoxy Exchange Reactions) Sample No./Wt.% Components 33 34 35 36 37 Polymer D - (MeO)₃Si PPO 98.00 97.80 cappedPolymer C - (EtO)₃Si PPO 98.00 97.80 97.80 capped Ti(OPr)₄ catalyst 0.20.2 0.2 ViSi(MeO)₃ 2.00 2.00 2.00 2.00 ViSi(EtO) 2.00

[0072] TABLE 5b Cure Times of Aged Compositions (Effects of AlkoxyExchange Reactions) Sample No. Physical Properties 33 34 35 36 37 AgedTemperature, ° C. 70 70 70 70 70 Aged Time, min. 30 30 30 30 30 SkinOver Time, min. 180  20 150  10 10

What is claimed is:
 1. A curable polymer having the structure:

wherein R is a hydrocarbon diradical which may include heteroatom and/orsilicone-containing groups or linkages; A and A′ may be each C₁₋₃₀linear or branched, substituted or unsubstituted aliphatic groups oraromatic-containing groups, with or without interuption by A may also bea carboxy, carbamate, carbonate, ureido, urethane or sulfonate linkage;n may be 0 or 1; R¹ and R² may be each substituted or unsubstitutedC₁₋₁₂ alkyl or aryl groups; R³ is a C₁₋₁₂ alkyl, alkenyl, alkoxy,aminoalkyl or aryl group, or a (meth)acryloxyalkyl group.
 2. The polymerof claim 1, wherein R is a polymer selected from the group consisting ofpolyesters, polyethers, polyolefins, polyurethanes, polysiloxanes,poly(meth)acrylates, polyepoxides and combinations thereof.
 3. Thepolymer of claim 1, wherein R is polypropylene oxide.
 4. The polymer ofclaim 1, wherein A is a propylene group.
 5. The polymer of claim 1,wherein R² is methyl.
 6. A curable composition comprising: (a) a polymerhaving the structure

wherein R is a hydrocarbon diradical which may include heteroatom and/orsilicone-containing groups or linkages; A and A′ may be each C₁₋₃₀linear or branched, substituted or unsubstituted aliphatic groups oraromatic-containing groups, with or without interruption by a carboxy,carbamate, carbonate, ureido, urethane or sulfonate linkage; n may be 0or 1; R¹ and R² may be each substituted or unsubstituted C₁₋₁₂ alkyl oraryl groups; R³ is a C₁₋₁₂ alkyl, alkenyl, alkoxy, aminoalkyl or arylgroup, or a (meth)acryloxyalkyl group. (b) a catalyst.
 7. The reactionproduct of: (a) a polymer having at least one pendant or terminalalkoxysilyl group thereon and being a member selected from the groupconsisting of polyethers, polyolofins, polyesters, polyurethanes,polysiloxanes, poly(meth)acrylates, polyepoxides and combinationsthereof; and (b) a catalyst.
 8. A method of making an alkoxysilylendcapped polymer, comprising the steps of: reacting a first reactanthaving the structure: HO—R—OH wherein R is a hydrocarbon diradical whichmay include heteroatom and/or silicone-containing groups or linkages,with a second reactant a silyl having one end terminating with anisocyanate group and another end terminating with at least two alkoxygroups attached to a silicon atom thereof, wherein R and the polymericbackbone of the second reactant are selected from the group consistingof polyesters, polyethers, polyolefins, polyurethanes, polysiloxanes,poly(meth)acrylates, polyepoxides and combinations thereof, andproviding for reaction as a third reactant a methoxy silane in amountsand for a time sufficient to achieve alkoxy exchange with saidalkoxysilyl endcapped polymer.
 9. The polymer of claim 8, wherein R isan alkylene oxide.
 10. A composition having controlled moisture curespeed comprising the reaction product of: (a) an alkoxysilyl endcappedpolymer having a backbone selected from the group consisting ofpolyesters, polyethers, polyolefins, polyurethanes, polysiloxanes,poly(meth)acrylates, polyepoxides and combinations thereof; (b) analkoxysilane present in sufficient amounts to permit alkoxy exchangewith the alkoxysilyl endcapped polymer; and (c) a catalyst.
 11. Themethod of claim 8, further including the step of compounding theresultant reaction product with a methoxy silane in amounts and for atime sufficient to allow for alkoxy exchange to take place.
 12. Thecomposition of claim 6, wherein the catalyst is a transition metalcomplex.
 13. The composition of claim 6, wherein the catalyst isselected from the group consisting of tin catalysts, titanium catalysts,metal alkoxide catalysts and combinations thereof.
 14. The compositionof claim 6, wherein the catalyst is selected from the group consistingof bases, acids, and quaternary salts.
 15. The composition of claim 6,wherein the catalyst is selected from the group consisting of amines,phosphines, dialkyl tin dicarboxylates, the titanates,tetraalkylphosphonium salts, metal oxides, and carboxylic acids.
 16. Themethod of enhancing the rate of transesterification comprisingpermitting first and second reactants, each having a different alkoxygroup pendant thereon to undergo transesterification in the presence ofa titanium or metal alkoxide catalyst.
 17. A composition havingcontrolled moisture cure speed comprising the reaction product of: (a)an alkoxysilyl endcapped polymer having a backbone selected from thegroup consisting of polyesters, polyethers, polyolefins, polyurethanes,polysiloxanes, poly(meth)acrylates, polyepoxides and combinationsthereof; (b) an alcohol present in sufficient amounts to permit alkoxyexchange with the alkoxysilyl endcapped polymer; and (c) a catalyst. 18.A method of controlling the cure speed of an alkoxy silyl functionalpolymer, comprising the steps of: providing an alkoxy silyl functionalpolymer having two or more different alkoxy groups; providing a curecatalyst therefor; and exposing the alkoxy silyl functional polymer andthe catalyst to conditions sufficient to cure the alkoxy silylfunctional polymer, wherein the identity and/or amount of the two ormore different alkoxy groups controls the cure speed of the alkoxy silylfunctional polymer having two or more different alkoxy groups thereon.